mjhjmtu

I'd like to find a way to find a given file by looking upward in the directory structure, rather than recursively searching through child directories.

There's a node module that appears to do exactly what I want, but I don't want to depend on installing JavaScript or packages like that. Is there a shell command for this? A way to make find do that? Or a standard approach that I just wasn't able to find through Googling?

This is a direct translation of the find-config algorithm in generic shell commands (tested under bash, ksh, and zsh), where I use a return code of 0 to mean success and 1 to mean NULL/failure.

findconfig() 
 # from: https://www.npmjs.com/package/find-config#algorithm
 # 1. If X/file.ext exists and is a regular file, return it. STOP
 # 2. If X has a parent directory, change X to parent. GO TO 1
 # 3. Return NULL.

 if [ -f "$1" ]; then
 printf '%sn' "$PWD%//$1"
 elif [ "$PWD" = / ]; then
 false
 else
 # a subshell so that we don't affect the caller's $PWD
 (cd .. && findconfig "$1")
 fi

Sample run, with the setup stolen copied and extended from Stephen Harris's answer:

$ mkdir -p ~/tmp/iconoclast
$ cd ~/tmp/iconoclast
$ mkdir -p A/B/C/D/E/F A/good/show 
$ touch A/good/show/this A/B/C/D/E/F/srchup A/B/C/thefile 
$ cd A/B/C/D/E/F
$ findconfig thefile
/home/jeff/tmp/iconoclast/A/B/C/thefile
$ echo "$?"
0
$ findconfig foobar
$ echo "$?"
1

A simple loop of checking the current directory and if it's not found then strip off the last component would work

#!/bin/bash

wantfile="$1"

dir=$(realpath .)

found=""

while [ -z "$found" -a -n "$dir" ]
do
 if [ -e "$dir/$wantfile" ]
 then
 found="$dir/$wantfile"
 fi
 dir=$dir%/*
done

if [ -z "$found" ]
then
 echo Can not find: $wantfile
else
 echo Found: $found
fi

For example, if this is the directory tree:

$ find /tmp/A
/tmp/A
/tmp/A/good
/tmp/A/good/show
/tmp/A/good/show/this
/tmp/A/B
/tmp/A/B/C
/tmp/A/B/C/thefile
/tmp/A/B/C/D
/tmp/A/B/C/D/E
/tmp/A/B/C/D/E/F
/tmp/A/B/C/D/E/F/srchup

$ pwd 
/tmp/A/B/C/D/E/F

$ ./srchup thefile
Found: /tmp/A/B/C/thefile

We can see that the search went up the tree until it found what we were looking for.

One way to do it:

#! /bin/sh
dir=$(pwd -P)
while [ -n "$dir" -a ! -f "$dir/$1" ]; do
 dir=$dir%/*
done
if [ -f "$dir/$1" ]; then printf '%sn' "$dir/$1"; fi

Replace pwd -P by pwd -L if you want to follow symlinks instead of checking physical directories.